Field of the Invention
The present invention relates to a signal processing method, an acoustic wave processing apparatus, and a recording medium.
Description of the Related Art
As one of optical imaging techniques, photoacoustic tomography (PAT) has been widely used. In the photoacoustic tomography, a subject is irradiated with pulsed light so that acoustic waves generated in an inside of the subject are detected, and signals of the acoustic waves are analyzed so that information on optical characteristic values in the inside of the subject is visualized.
Imaging of comparatively-thin blood vessels, which form a tumor, has been attempted using a PAT apparatus for measurement of a living body. However, acoustic waves generated from these thin blood vessels and reception signals obtained by detection elements are comparatively weak, and an image of desired quality may not be obtained unless noise and any artifact are appropriately removed. An artifact means an image which appears as if something exists although nothing exists in practice.
One of the techniques of removing artifacts is disclosed in Japanese Patent Laid-Open No. 2011-00414. In the disclosure, removal of artifacts caused by a transient response due to interface acoustic waves is to be attained. A plurality of reception signals obtained at the same time point are added to one another, a signal obtained by the addition is standardized using a maximum amplitude, among amplitudes of the plurality of reception signals, as a reference, and thereafter, the signal is subtracted from the reception signals.